1. Field of the Invention
The present invention relates to a light adjusting apparatus that adjusts light by inserting/retracting an incident light adjusting section into/from an optical path of incident light.
2. Description of the Related Art
Image pickup devices having an image pickup function are widely used in a variety of fields, among which there is a field of small image pickup devices having a relatively small shape. Some examples of such a small image pickup device include an electronic endoscope, an optical microscope provided with an image pickup function, a portable device provided with an image pickup function or a micro video scope.
Since priority is given to miniaturization in conventional small image pickup devices, a fixed focus lens, a fixed aperture diaphragm, a fixed characteristic filter or the like are adopted as optical elements such as a lens, a diaphragm and an optical filter.
In contrast, high image quality has been also required for these small image pickup devices in recent years, and there is a growing demand for adopting a focus lens, a variable diaphragm, a variable characteristic filter or the like as optical elements of the aforementioned light adjusting apparatus, that is, a demand for functions as a light adjusting apparatus that adjusts light.
Thus, many techniques are being proposed which seek to reduce sizes of light adjusting apparatuses so as to be applicable to small image pickup devices.
For example, FIG. 1 or FIG. 2 of Japanese Patent Application Laid-Open Publication No. 9-22042 describes a configuration as shown in FIG. 24 attached to the Specification of the present application. Here, FIG. 24 is a plan view illustrating an example of a configuration of a conventional light adjusting apparatus.
A circular (more specifically, substantially C-shaped) coil core member (yoke) (103) wound with an excitation coil (104) is placed around a taking lens (102) fixed to a base plate (101). Furthermore, a permanent magnet (105) is placed in a cut-out portion of this substantially C-shaped coil core member (103) so that both core member ends (103a, 103b) of the coil core member (103) face the permanent magnet (105). By configuring a closed-magnetic circuit of an electromagnetic drive apparatus in this way, it is possible to increase the volume of the coil core member (103) around the taking lens (102) and obtain a sufficient drive force.
Furthermore, FIG. 1 or the like of Japanese Patent Application Laid-Open Publication No. 2010-186168 describes a configuration provided with a substantially C-shaped coil core member disposed on a substrate, a coil wound around this coil core member and an axial magnet disposed in a cut-out portion of the substantially C-shape, and a technique of providing a cut-out portion for receiving the axial magnet on a substrate and facilitating assembly of the axial magnet to the substrate. The above-described Publication describes the use of a separate bearing member (stopper portion) to prevent dropout of the axial magnet from the cut-out portion. Furthermore, FIG. 3, FIG. 9 and FIG. 10 of the Publication describe that a plurality of light adjusting means are arranged in the light adjusting apparatus.
The axial magnet is disposed at a certain distance from both core member ends of the coil core member so as to prevent interference to rotation thereof.